Despite the rapid development of mobile radio networks and the Internet, the line-connected public telephone network (landline network) is still, by far, the most important professional and private source of communication in industrialized countries. In Germany, the public telephone network has almost 50 million subscriber lines connected to approximately 1800 local exchanges and approximately 600 trunk exchanges. With the introduction of the ISDN (Integrated Services Digital Network) on the basis of the digital switching technology of the public telephone network, relevant additional services are provided for owners of ISDN lines. These additional services offered attracted more than 3 million customers for ISDN lines by as early as 1997, and this number continues to increase at a great rate.
The services offered by the (digital) public telephone network need to stake a claim on the market in the face of those offered by the mobile radio networks and the Internet, however, whereby the services offered need to be constantly extended. The providers of the public mobile radio networks are naturally subject to the same compulsion.
Certainly one of the most important services for the subscribers is call forwarding or redirection, which for years has been part of the services offered by the landline network and also by the mobile radio networks and, since the setup of suitable interfaces, has also become possible between these networks.
Another important service which is of central significance for the mobile radio networks, but is also becoming increasingly relevant to the subscribers on the landline network, is the option of storing voice or text messages within the network in a so-called mailbox or telebox. Part of this service is notification of the subscriber about a voice or text message which has been received via a so-called Message Waiting Indication (MWI). The progressive linking of data networks, in particular of the Internet, to the public telephone networks results in the notification of a subscriber about e-mails which he/she has received via a so-called E-mail Waiting Indication (EWI) also gaining increasing practical significance.
The present invention is, therefore, directed toward developing the public telephone network such that the user""s utility value associated with voice and text storage in the network and also with services in connection with the transmission of e-mails is increased further.
The present invention encompasses the fundamental concept of increasing the practical utility value of the service features of Message Waiting Indication and E-mail Waiting Indication by virtue of these service features reaching the user not only on the line on which the relevant voice or text message or e-mail has been received, but also at the location in which he/she is currently situated. It also encompasses the concept of developing the service of call forwarding to this end such that it also permits forwarding of an MWI or EWI.
In preferred embodiments of this invention, interfaces are produced between landline networks and mobile radio networks such that the proposed forwarding is possible in both directions; landline network/mobile radio network and mobile radio network/landline network and also between the mobile radio networks.
One provision within the scope of the present invention is that the exchanges or service switching points in the telephone network contain parts for checking the presence of call forwarding on a subscriber line associated with them in response to the reception of an MWI and/or EWI on this subscriber line. They also contain parts for linking the MWI or EWI to the destination call number which was set within the context of the call forwarding, as well as parts for forwarding the MWI or EWI to the exchange responsible for the destination call number or to the competent service switching point. The use of these parts provides the telephone customer with the same service, in terms of the signaling of an MWI or EWI, on a call forwarding line as on his/her standard line, which distinctly increases the attractiveness of the network""s dedicated storage capabilities and, hence, the attractiveness of the network overall.
To prevent a forwarded MWI or EWI from being rejected by the new line""s associated list of those mail servers which are authorized to transmit an indication to this line, the forwarded MWI/EWI needs to be provided with an additional flag identifying it as forwarded information. For particular systems, the xe2x80x9cTimexe2x80x9d field of the report is suitable for this purpose. The flag needs to be set by the exchange or the service switching point for the call forwarding destination line.
In another preferred embodiment of the present invention, signaling parts are provided for acknowledging that the MWI/EWI has been forwarded, or that the forwarding has been unsuccessful or has involved an error, to the mailbox or the originator. In the first case, if an error occurs, it is possible to make a fresh attempt at forwarding; in the latter case, setup of the proposed novel service feature is linked to the additional advantage that each subscriber can, by reason of this, be certain that the other party has actually become aware of the arrival of a message which has been sent from the subscriber to a mailbox in the telephone network. There would, accordingly, be exceptions only in the case of an error, notification of which is explicitly sent to the originator.
In a similar way as in the case of call forwarding from one network line to another, the scope of the present invention is also intended to cover the forwarding of an MWI/EWI from one extension to another in a private branch exchange. This naturally requires that the private branch exchange be appropriately designed as such.